Method and apparatus for treating sludge



Jan. 9, 1923, 1,441,731. W. Tl. Tv'lATHlS.

METHOD AND APPARATUS FOR TREATING SLUDGE.

FILED mmrzs, 1921 2 SHEETS ShEET 1.

N gwwzmioz fi 16 21am Jan. 9, 1923. 1,441,731.. W. R. MATHIS.

METHOD AND APPARATUS FOR TREATING SLUDGE.

FILED MAY 26, 192i- 2 SHEETS-SHEET Z.

Patented Jan. 9, 1923.

STATES oar-ice,

I WALTER JR. MATCHES, 0F ATLANTA, GEORGIA.

METHOD AND APPARATUS FOR TREATING: SLUDGE.

Application filed May 26,

To all whom it may concern:

Be it known that I, WALTER R. MATHIS, a citizen of the United States, residing at Atlanta, in the county of Fulton and Statemove from the raw water of water works valuable clay products, adapted for use in various arts and industries such as the ceramic art, paint pigments etc.

Another object of the inventionls toreclaim the coagulant from the sludge ,in an economical way. Economical asto time required, results obtained and apparatus employed.

Another object of the invention-1s to SIID; plify the mechanical devices, that have here tofore been employed in the control of coagulating chemicals and to render the same more efficient.

range the devices and methods employed so that they may quickly and readily be adapted to anysystem of coagulant feedingand control as now in general use.

Another object of theinvention is to eliminate certain objectionable features of the present method of coagulant control so that less labor and supervision will be necessary to keep the devices in repair. 7

With the foregoing objects outlined and other objects in view which will appear as the description proceeds, the invention consists in the novel features hereinafter described in detail, illustrated in the accompanying drawings and more particularly pointed out in the appended claims.

Referring to the drawings:

Figure 1 is a partial sectional view of the most of the devices employed.

Figure 2 is a plan view of the devlces shown in Figure 1.

Figure 3 is an enlarged sectional view of rear. Serial in. 472,275.

the digesting, mixing, crystallizing tanks and drying vats, etc., shown in Figure 1.

I With the understanding that the same numerals designate like parts in all the views, 1 1s a tank to store the re-agent used to dissolve the coagulant and separate it from the "extraneous matter, in the present case and as an example, sulphuric acid is used. A predetermined amount of acid is allowed to pass through the valve 2 into a digesting tank 3 after which is added thereto slowly,

withconstant stirring, other substances to be descr1bed. These substances are mixed and stlrred by an agitator 4 operated by any suitable power, as by hand or by an electric motor 5.

After being thoroughly mixed and digested, the mixture now being in a pasty condition, the mass is allowed to escape from the tank 3 through'any suitable valve as 6 into a second tank, designated as a dissolving tank 7, through the spout 9. Into dissolving tank 7 water is discharged through the pipe 8 and valve as shown, in quantity suflicient to bring the digested coagulant contained in the mass into a water solution of the desired strength. The spout, or conveyor 9 is any convenient conduit from the bottom of tank Another object of the invention is to ar- 7 3 to the tank 7, the latter being conveniently placed to one side of the tank to provide apparatus-whereby an additional stirrer 10 After the water and the digested mass from the tank 3 has been thorou hly mixed and allowed'to stand in the tank it will be found that a thick deposit will be precipitated in the bottom of the tank 7 and that this deposit will consist of pure clay, in appearance snow white, and having properties that render it more or less valuable in the ceramic arts, or the useas paint pigment, since the deposit will be free from the com mon' clay impurities such as iron oxide, sand, organic matter, etc.

.The clay deposit from tank 7 may be run through a discharge pipe 12 onto a dehydrating or drying bed 13 having an especially arranged porous bottom 14 and through which the water, may be drained an arrangement for extending the stirring out throughthe pipe system 15 and thence discharged into the sewer or waste; or if it is desired to discharge all of this clay product directly in the sewer or waste the same may be accomplished by discharging directly from the tank 7 through the pipe 15.

After the mass containing the digested coagulant has passed through thetankj3 into the tank 7 and kept constantlyagitated with the required amount ofwater, the co,- agulant will be dissolved thereby and then may by syphoned from tank 7 into a solution storage tank 16 after it is freed from its deposit of clay and other foreign matter. 17 represents a crystallizing tank that may be used to crystallize the salt whenv it'is desired to store the coagulant in solid form. it

being supplied with the solution through a branch pipe 19 from the syphon 20.

The coagulant solution contained in the storage tank 16 may be measured in definite quantities through any orifice device 16' to the raw water infiuent, into the pipe 21. This pipe 21 brings the water from the water system mains.

22 represents suitably designed mixing chambers special features of which will be designated on individual installations, the,v function of which is to thoroughly mix the raw water and the chemicals (coagulants'). this being an especially necessary condition, with the raw water influent. After th water and the coagulant are thoroughlymixed in the mixing chamber 22 it is passed to'settling basing 23--23 conveniently supplied with hopper-shaped bottoms of the proper slope. These settling basins 23-- 23 have capacity carefully calculated and constructed so that the proper retention period is attained for the efiicient precipitation of the'suspended matter and other impurities being carried by the raw-water.- The sludge having been precipitated in the hopper shaped sumps of the settling basins, the partially purified water may be drawn from the top of these basins'and delivered to the filters 26 where the remaining sludge and impurities are removed. From thence the purlfied water is delivered to any suitable storage for distribution to the consumer.

A special arrangement of wash-water efliuent from the filter beds are provided to conduct the filter wash-water into the sludge draining pipe 24 together with thesludge removed from the settling basins 23-23.

At predetermined times the sludge from the bottom of the settling basins 2323 is passed through pipes 24 supplied with suitable valves 25 andallowed to pass onto the dehydrating beds 27 having a porous bottom arranged so as to be placed in service in sections as illustrated. Onthese sectional drying beds the sludge is freed of all -'tion the coagulating chemicals may be bought in the open market. The chemicals generally employed are aluminum sulphate,.

or iron sulphate. This material "is dissolved in water to the required strength in dissolving tank 7 as described and conducted into storage tank 16 from whence it is measured in definite quantities; through any-orifice device 16 into the raw water influent pipe 21 through the chemical solution pipe shown. 1

Ord-na'rily, the clay which I propose to collect in the dehydrating tank 13 is wasted,

. together-with the coagulants, both of which constitute a part of the sludge which collects in the bottom of the settling basins and upon the to of thefilter beds. These substances, whic usually passed'into'the waste. I am aware, however, that others have proposed to utilize this sludge as a coagulant, but it is new so far as I can ascertain to treat this sludge and use it as I propose, that is to say, this slud e is drawn from the bottom of the beds, and is assed to the dehydrating beds dried sludgeas a source of coagulants, after the process of separation as described heretofore, over and over to coagulate and reare valuable, have been and is drie I then propose to use this i move-the impurities in the raw water to e method I'have adopted is that after the sludge is dried on the dehydrating beds 27 I collect it in its dry state and re-deposit it in storage near the digestion tank 3 from which place it is proposed to reclaim the coagulants therefrom as described and after the first run of the coagulant through the system to use the same over and over again instead of having to buy new chemicals such as commercial filter alum to be dissolved in tank 7 I have found that I can do this and in some cases preserve as much as 95% of the coagulant originally dissolved in tank 7 Of course the substances and impurities in In other words, the sludge in combination with the sulphuric acid forms aluminum sul phate, water and When the,

sludge I is conducted from (the coagulating basinsfand the filterbedsto-the dehydrating Organic matter eolublein.

beds 27- and dried-atypical analysis woul show the following 'constituents':,"

Iron oxide and alumina; 18.17%fiq1ilvalenf to I I coagulants.

Matter insoluble in His 0 65.56%;

Total, on dry b sis'u'n 100.00%.

When the dried material (sludgeiis moved from the dehydrating beds 27 and re-' turned to the-storage to be used in the digestion tank 3 and then through the dissolving tank '7, itmaybe used in the place of the first charge of commercial alum, because at -thisstage of the process itfhas beenrecom "verted into a solution'that accomplishes the identical purpose for which the alumis used,

stance that would tend to e og-thefeeolinga-f besides being freev roman Qforeign subvalve or devices, or the chemical feed lines? Hence-the'system comprises the injection of thesolution from .the tank 16', thence through the measuring orifice 16", thence through the chemical feed line to the point of injection in the raw water influent pipe 21, thence to the mixing chamber 22 to gather with the water to be treated, thence to the settling basins 231-23, conductmg from the bottom of the coagulating basins the precipitated coagulant and the suspended matter (sludge) tothe dehydrating beds.

27 and drying the same,'andconducting-the partially purified and settled water from the top of'the settling basins 23-23 to the filter beds to entrap-the remaining sludge for the. purpose'of reclamation of the same, as wellv as to complete the purification of the water, then using the dried sludge as a source of coagulating chemical by' digesting in sulphuric acid and dissolving the resultantmass in water to separate the sulphate solution from the insoluble and organic matter and then decanting the sulphate solution into the. storage tank 16 to be used over again as before stated in the beginning of this description of the cycle. -The insoluble clay product that remains in the tank 7 may be drawn off and dried in the dehydrating bed 13 for further valuable purposes as explained before. i

ll find that it is only necessary to add 7 about five to ten per cent of ordinary com mercial filter-alum, or its equivalent of ore, to the ordinary procedure of water treatment, to supplement the yield of coagulant from the sludge treated by the process here described to keep the system running indefinitely, thus reducing the cost to a minimum. I have found in actual practice that the dried sludge is as .efiicient and much less trouble to manipulate than the sludge without dryingon accountv of the freedom of insoluble matter in the coagulating solution Eseribed;

jvalves, etc. a

1 iti nv v this, process thereis obtained a considerable a.pmancea,igtvhieh, amatmeat-a e in r y' ter. ja Pm-"l C s fitt ngs," n

quantity 1 of pure; 'lola'y as. 'heretoforef der. I I I oll'eetible .into; tankl13 i which' "is" 01f considerable-valuecommerdiallyi 1 i f It is apparent; that-"my. .rne'th to. the ab o ve at an... of

we jment of sludge ma be changed: -1 n various details and the apparatus ana evices used.

Jere-capable of diflerent 'fbrms' and changes What I claim is without' materially altering 'thefinvention.

apparatus foritreating' sllidge Y1 A Erisin'g a mixing tankjadapted-tobe, con-f "nectedtoa'water main, a mixin'g'chamber chambers connected to the mixing chamber '-.and a"dehydrating vat with a porous bottom connected to the bottoms-of the settling chain'- also connected to'the water main, settling fibers whereby suitable chemicals maybe in-' troduced in desired quantities into the water mam "to coagulate, impurities of water, the nnxing chambers -producin'g-.-- a' thorough m 1x1ng.of the chemicalswith' the water and .the resulting coagulant drawn ofi' from the bottom of the settling :chambers and ,conducted to thedehydrating vat for drying purposes.

2. An apparatus'to be used in the treatment of sludge comprising chemical mixing vats provided with stirrers,- a dehydrating vat for drying the clay separated from the chemicals, connections between the clay dehydrating vat and the chemical mixing vat, connec tions from the chemical mixing vat to a water main,'a mixing chamber connected to the water main, a settling chamber, having a comcal bottom, a second dehydrating vat cals to coagula e the impurities in the water,

separating the coagulant from the water, drying the same and using it as a chemical to again purify the water of the system.

, 4. The process of purifying chemically the water in water mains comprising mixing of the chemicals containing a comparatively large volume of cla allowing the clay to settle, drawing it o and drying the same, conducting the purified chemicals to a water for drying the coagulantsin the settling chamber the coagulated materials in, the,

water to a dehydrating vat and drying the same and conducting from near the top of.

the settling chamber the-purified Water and delivering it into the. main andusing the dried coagulant and other chemicals to purify more Water.

5. The method of treating water of .Water Works comprising the mixing ofsuitable "chemicals to be used and allowin the impurities in the samertosettle, intro ucing the mixed and purified chemicalsinto the Waterof a water main, mixing the Water and chemicals to coagulate the impurities inthe- Water in settling chambers, drawing from the top of'the chambers the partially clarified water and conducting it, tothe filter bed, separat ing' the coagulant from the water'left in the settling chambers and using the coagulant as a chemical to again purify the-Water of the system;

-' [WALTER R. MATHIS.

In testimony whereof I aflix my signature. 

